It is known in the formation of emulsions that are consisting of oil and water to apply forces to these emulsions to decrease the size of the oil phase droplets or particles. It is known to utilize mills such as colloid mill, high speed shear mixer, and various jet homogenizer apparatus to do this. Further is known use stacks of perforated plates through which the dispersion is forced. The use of these types of apparatus for decreasing particle size has the disadvantage that it results in emulsions that do not have a uniform particle size distribution. Further these devices require high energy in order to accomplish the particle size reduction.
It is also known to place ultrasonic probes into containers of emulsion in order to decrease the particle size. However, this technique results in oil and water emulsions that have a wide distribution of particle size. Further, it has been known to place ultrasonic probes into streams of particles and liquid in order to pass these particles by the probe to reduce the particles size. These also have the disadvantage that the particles are not uniform in size.
In the formation of photographic materials that are dispersions of particles coupler material and permanent solvent suspended in a gelatin water solution, there is a continuing need for accurate particle sizing of these solutions. These suspensions are more properly in chemical practice called emulsions; however, in the photographic art it is commonly known to refer to these emulsions as "dispersions" of couplers. In the photographic art, "emulsions" refer to suspensions of silver halide particles.